DESCRIPTION (Taken from the Investigator's Abstract) It is widely believed that Parkinson's Disease develops when a combination of environmental exposures and genetically determined susceptibility leads to loss of dopamine producing neurons in the substantia nigra, the appearance of Lewy bodies in degenerating neurons, and diminished levels of dopamine in the striatum. The investigators plan to quantify two neuropathologic markers of these specific neurodegenerative processes: neuronal loss in the substantia nigra and diminished striatal dopamine levels in the brains of 600 Japanese- American male decedents who were participants in the population based, prospective Honolulu Heart Program/Honolulu-Asia Aging Study. The idea that these measures reflect the fundamental pathogenic processes ultimately leading to Parkinson's Disease will be examined by relating them to extra-pyramidal signs and impaired olfaction, possible indicators of preclinical Parkinson's Disease. Upon being determined quantitatively, these markers will be used as continuous endpoint variables in an effort to identify occupational, dietary and other environmental exposures that influence the development of these processes. Exposure data are available from standardized interviews and examinations in 1965-1967, 1968-1970, 1971-1974, 1991-1993, 1994-1996, and 1996-1998. This analytic strategy has the advantages of greatly enhanced statistical power (since the underlying processes are far more common than the clinically diagnosed illness), and the ability to focus on links between specific risk factors and discreet pathologic endpoints. The project will utilize the accumulated and ongoing resources and infrastructure of the National Institute on Aging funded Honolulu-Asia Aging Study, as well as the Department of Defense and Veterans Affairs funded projects regarding the association of neurotoxins and other exposures with Parkinson's Disease and Parkinsonism in the cohort. Funding for this proposed project will be used for the additional neuropathologic measurements, and for the substantial analyses and presentation activities that will be conducted to utilize the available information.